1. Field of the Invention
The present invention relates to an information leakage countermeasure technique, applicable in particular to the generation of images including e.g. confidential, proprietary or commercially sensitive information by an image forming apparatus.
2. Description of the Related Art
The recent progress of IT in offices has led to a growing interest in security. The privacy of organizations as well as the privacy of individuals may in instances be jeopardized as manifested by, for example, an occurrence of leakage of company-owned information.
To tackle the problems described above, companies are attempting to prevent leakage to the outside by introducing IT (Information Technology) mechanisms such as setting access privileges for computerized confidential information or setting a monitoring apparatus on a firewall. Alternatively, companies are taking measures such as prohibiting notebook or laptop PCs, USB memories and other portable media from being carried out from and/or carried into the office. Computerized confidential information can be protected to a certain degree by implementing measures using an IT mechanism such as described above. This is because electronic information can only be referenced using such an IT mechanism, and also because an IT mechanism can be readily introduced therein.
On the other hand, when confidential information is printed on a medium such as paper by an image forming apparatus or the like, it is difficult to check or prevent paper, on which organizational secrets or private information of individuals are printed, from being carried out, for example, of a building. Accordingly, it is possible to circumvent conventional IT mechanisms such as described above. This makes restricting paper from being carried out more difficult as compared to computerized confidential information, presenting a challenge to maintaining security.
Various information leakage countermeasure techniques have been conventionally devised in order to deal with this problem.
As a first information leakage countermeasure technique, a conventionally-devised system involves using a known digital watermarking technique or an information embedding technique such as for example a two-dimensional barcode to embed tracking information into a paper medium itself in addition to an original image during printing. According to such systems, when information leakage involving a paper medium occurs, the tracking information can be extracted by analyzing the leaked original document. Consequently, since it is now possible to pursue those responsible for improperly taking out an original document based on tracking information included in the original, a deterrent effect on illicit actions can be expected.
In addition, as a second information leakage countermeasure technique, a conventionally devised technique involves using, for example, a known watermarking technique or a two-dimensional barcode technique to embed copy restricting information for prohibiting copying onto a medium such as paper during printing. An image forming apparatus accommodating such techniques is capable of detecting whether or not copying is enabled by extracting the copy restricting information from the original during copying, making it possible to control continuation or termination of copying on a per page basis. Furthermore, techniques have been proposed in which, aside from just copy restriction where copying is simply enabled or disabled, password information and authorized user information are embedded as condition information, whereby copying is only permitted to specific users based on the condition information. For example, one such system is disclosed in Japanese Patent Laid-Open No. 2003-280469. Hereinafter, tracking information and copy restricting information described above shall collectively be referred to as “additional security information”.
Moreover, many processing techniques referred to as “advanced modes”, in which printing is performed after subjecting an image to processing in accordance with a user's request, are conventionally implemented in copiers and other image forming apparatuses. Representative examples include the following:    Enlarged/reduced printing function for enlarging/reducing the size of an image with respect to an input original and printing the image    Area specifying function for arbitrarily selecting an area of an image of the original to be printed    Moving function for moving an image of the original longitudinally and/or laterally and printing the image    Image creating function for performing mirror image inversion or negative-positive reversal on an image
Conventionally, these advanced modes are applicable not only to ordinary originals but also to originals embedded with the additional security information described above.
However, with the conventional techniques described above, because it may not be possible to extract and read additional security information in printed images to which certain advance mode settings have been applied during a copying operation, there is a problem in that desired security measures may not be implemented.
In addition, while offices in which originals embedded with additional security information are distributed may choose to ban advanced mode settings and printing under such modes, such bans have an adverse effect of inhibited availability because a user is no longer able to select advanced modes when performing copying.